This invention relates to a system for manufacturing structures of cementitious materials, and to unique techniques for finishing various features of the structures. The construction industry is basically unchanged in materials and processes for hundreds of years, while during this same time most other industries have been revolutionized. The consequence is that there is vast room, and need, for improvement in the construction industry, for the lack of improvement has resulted in escalating costs and a compounding of negative impact on the environment.
The construction industry has sought alternative building
The construction industry has sought alternative building materials and techniques in order to limit the traditional expenses of construction. The costs include the high energy costs of manufacturing, increasing scarcity of quality materials and the rising cost of available materials, and increasingly expensive construction labor. Regrettably, the majority of solutions employed so far have only resulted in an increasingly inferior quality to finished product. Consumers desire to lessen the negative environmental impact (i.e.: deforestation, mining and pollution from manufacturing) and negative health effects (i.e.: fluorocarbons and other harmful gases, mold from decay) of some building materials. These factors have forced home builders in particular to consider new construction materials. These new materials must be versatile, easy to use, durable, and energy efficient.
An alternative to the conventional building materials is what may be called Autoclaved Aerated Concrete, hereinafter referred to as “AAC”. AAC is superior to current building materials and is extremely environmentally friendly. That is, the teachings hereof will substantially reduce global warming by preserving forests. While this invention applies to any cementitious material which can employ the teachings of this invention, AAC is a preferred material and the further description will be so limited.
AAC was invented in the early 1900's and consists of a mixture of cement, aluminum powder, lime, water and finely ground sand. This mixture expands dramatically, and this “foamed” concrete is allowed to harden in a mold, followed by curing of the hardened mixture in a pressurized steam chamber, or autoclave. Commercial production of AAC began in the 1930's, and presently more than 31 million cubic meters have been produced worldwide.
Compared to wood, steel and standard concrete, AAC is a clearly superior material as it is fire proof, termite proof, self insulating, sound insulating, non decaying and does not rust. Compared to concrete, AAC weighs 30% less than traditional concrete masonry units. Additionally, AAC is well known as an environmentally friendly construction material with certain manufacturing plants receiving recognition as being “Green Factories.” Compared to the energy consumed in production of many other basic building materials, only a fraction is required to produce AAC. Raw materials consumption is very low for the amount of finished product produced. In the manufacturing process, no pollutants or toxic by-products are produced. AAC is also completely recyclable.
AAC is an inorganic material that contains no toxic substances. It does not slowly decompose nor emit a gas. Since AAC is both a structural and insulation material it allows the elimination of other materials that can contribute to poor indoor air quality. Due to its inorganic structure, AAC also eliminates the food source condition required to be present for microbial growth to occur. Thus, AAC is resistant to water penetration and decay. As it is a solid cementitious building material, insect (roaches, ants) and rodent (rats, mice) infestation is impossible within walls and floors as there are no cavities as now occurs in standard frame construction.
Further, AAC is non-combustible, so in the case of fire it can help prevent the fire from spreading to other rooms. During a fire, no toxic gases or vapors are ever emitted from inorganic AAC. As building methods using AAC include using solid blocks and panels with very simple connection details, the ease of construction helps to ensure a monolithic, highly fire-resistant wall.
AAC buildings, as described by this invention, can be very energy efficient. This efficiency is due to a combination of high R-value, thermal mass and air-tightness. AAC is the only product currently available that meets Germany's stringent energy codes without added insulation. It is well documented that the R-value of a mass product need not be as high as that of light frame construction, to perform thermally efficiently.
AAC products are unfinished. Depending on the building use or the aesthetic requirements, AAC may be coated with an exterior surface finish of approved stucco, stone, brick-veneer, wood siding with furring, or a combination thereof. On the interior AAC usually has sheetrock installed over furring strips due to utilities and numerous joints of blocks.
While the construction industry recognized certain advantages in the use of AAC components for building, no system exists to effectively take advantage of the superior qualities of AAC in a cost effective manner. In fact, even though AAC is itself considered a vastly superior construction material than current construction industry standard wood, steel and/or concrete, the prior methodologies employed in AAC construction cause ACC to be so much more labor intensive and costlier than current standard construction materials, that the negatives of prior methodologies of AAC construction basically outweigh AAC's inherit advantages and so prohibit AAC from being considered as a viable alternative. The teachings of this invention not only eliminate these prohibitive negatives, they so facilitate the construction of AAC habitats that AAC habitats now can be built in less time and for less end use cost than conventional materials, with the underlying theme being the construction industry's prerequisite “simpler, better, cheaper” motto.